Issue 21210002: Avoid redundant smi check for Math.abs

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Issue 21210002: Avoid redundant smi check for Math.abs (Closed)

Created:
7 years, 4 months ago by weiliang.lin2

Modified:
7 years, 4 months ago

Reviewers:
Jakob Kummerow

CC:
v8-dev

Base URL:
http://v8.googlecode.com/svn/branches/bleeding_edge/

Visibility:
Public.

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Description

Avoid redundant smi check for Math.abs Replaced by https://codereview.chromium.org/21180004/.

Patch Set 1 #

Total comments: 2

Created: 7 years, 4 months ago

Download [raw] [tar.bz2]

		Unified diffs	Side-by-side diffs	Delta from patch set	Stats (+2 lines, -2 lines)			Patch
	M	src/ia32/lithium-codegen-ia32.cc	View		1 chunk	+1 line, -1 line	1 comment	Download
	M	src/x64/lithium-codegen-x64.cc	View		1 chunk	+1 line, -1 line	1 comment	Download

Messages

Total messages: 2 (0 generated)

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Jakob Kummerow

7 years, 4 months ago (2013-07-31 12:27:27 UTC) #2

This does not LGTM yet, see below.

Also, please port the patch to ARM. We don't want platforms to diverge if it can
be avoided.

https://codereview.chromium.org/21210002/diff/1/src/ia32/lithium-codegen-ia32.cc
File src/ia32/lithium-codegen-ia32.cc (right):

https://codereview.chromium.org/21210002/diff/1/src/ia32/lithium-codegen-ia32...
src/ia32/lithium-codegen-ia32.cc:3834: } else if (r.IsInteger32() || r.IsSmi())
{
You can use r.IsSmiOrInteger32() here.

https://codereview.chromium.org/21210002/diff/1/src/x64/lithium-codegen-x64.cc
File src/x64/lithium-codegen-x64.cc (right):

https://codereview.chromium.org/21210002/diff/1/src/x64/lithium-codegen-x64.c...
src/x64/lithium-codegen-x64.cc:3460: } else if (r.IsInteger32() || r.IsSmi()) {
This code is wrong. EmitIntegerMathAbs() uses testl/negl, which don't handle
Smis correctly. Repro case:

var a = [-1, -2];
function foo() {
  return Math.abs(a[0]);
}
print(foo());
print(foo());
%OptimizeFunctionOnNextCall(foo);
print(foo());

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